Just because you aren’t bingeing on snacks and desserts, it doesn’t mean you won’t gain weight or develop diabetes. Here are 5 secret reasons you may be putting on pounds and ways to fight them...

These days, when nearly two-thirds of American women are overweight or obese, the reasons we pack on pounds aren’t always clear. In fact, health experts now point to our modern world as an underlying reason for weight gain, which puts you at risk for diabetes and other dangerous diseases.

Our environment is “toxic for maintaining a healthy body weight,” says Suzanne Phelan, Ph.D., assistant professor of psychiatry and human behavior in the Brown Medical School Weight Control and Diabetes Research Center in Providence, R.I.

We already know the main obstacles to maintaining a healthy body mass: eating too much, exercising too little, too many high-calorie temptations each day. But there are hidden hazards as dangerous as the Cheesecake Factory’s dessert menu.

Your best defense against these sneaky “fat traps”? Information. Here’s how to avoid getting snared.

Fat Trap #1: Giant PortionsPortion sizes in restaurants and store-bought packaged foods have increased tremendously over the past 25-30 years. It’s no coincidence that Americans have developed super-sized waistlines too.

The serving size on a store-bought box of cookies surpasses government recommendations by as much as 700%. (With pasta, it’s 480%; muffins, 333%; steak, 224%.)

Even cookbooks have jumped onto the jumbo bandwagon: Some dessert recipes in a 1994 edition of The Joy of Cooking are identical to the 1964 version, except you get fewer servings from the same pan.

Here are some surprising examples of how much a single serving has increased over the past generation:

Escape the trap: Eat and drink like it’s 1979Large portions have extra calories, carbs and fat. And they encourage you to eat much more than your body needs. Consuming less is easier said than done, but here are some tricks:

Use smaller dishes and taller glasses. In 2005, Cornell University researchers found that people serve themselves more food when using larger spoons and plates, and less with smaller dinnerware. When allowed to have as much as they wanted, those eating from 17-ounce bowls consumed 31% less ice cream than those eating from 34-ounce bowls; and those using a 2-ounce scoop served themselves 15% less than those with a 3-ounce scooper. None of the participants – all nutrition experts – noticed the discrepancies.

The same Cornell scientists found that people pour 20%-30% more beverages into short, squat glasses than into tall, thin ones.

Take a 25% smaller portion of everything you eat, except vegetables.According to the American Institute for Cancer Research, simply eyeballing a serving size and then reducing it by one-quarter helped women eat 10% fewer calories – about 250-500 calories daily.

When eating out, share and split everything – or order from the kids’ menu.Since restaurant servings have increased astronomically in the past few decades, split your appetizer, salad, entree and dessert – or just order appetizers and skip entrees entirely – to ensure that you’ll eat a normal-size amount of food.

Fat Trap #2: Portly PeersObesity can spread, just like a social virus.

In a widely publicized 2007 Harvard Medical School study, researchers evaluated more than 12,000 people over 32 years. They found that when people gain weight, their close friends, siblings and spouses do too. In fact, if a close friend puts on pounds, you’re 57% more likely to gain weight.

The reason, researchers theorize, may be that obese people revise their perception of acceptable body size, and such thinking spreads among peers.

Fat Trap #3: Burning the Midnight OilOnly 26% of us get eight hours of sleep each night, down from 35% just 10 years ago. And researchers believe that this decrease in sleep duration is directly related to a higher body mass.

A 2006 Case Western Reserve University study looked at the snooze habits of more than 68,000 women, and found that those who slept less than seven hours a night were more likely to add weight.

Women who got only six hours a night were 12% more likely to gain, and those who slept just five hours faced a 33% greater chance of gaining an average of more than 30 pounds.

There’s evidence that lack of sleep impacts appetite-regulating hormones such as ghrelin and leptin. But not all of the women who became heavier were eating more – the sleeplessness alone may have somehow caused them to gain weight.

Escape the trap: Sleep before midnight The study’s authors believe their findings lead to one conclusion: “Increasing sleep time among those sleeping less than seven hours per night may represent a novel approach to obesity prevention.”

Fat Trap #4: Skipping BreakfastGenerally, people who maintain weight loss eat breakfast, Phelan says. In fact, nearly 80% of the people who drop pounds in the National Weight Control Registry, which tracks successful losers, eat a morning meal every day.

A 2008 University of Minnesota study offers more proof: When more than 2,200 adolescents and young adults were followed for five years, the breakfast eaters gained less weight and had lower BMIs than their peers.

Researchers don’t know why skipping the morning meal puts you at higher risk for weight gain, but they suspect that eating breakfast has a positive impact on metabolism and appetite.

“It may help manage hunger during the rest of the day and keep blood glucose at an even keel,” Phelan says.

Escape the trap: Start mornings rightA healthy breakfast doesn’t mean coffee and donuts or a stack of syrup-soaked pancakes. Refined breads and cereals also can make you tired and famished later on, so you’ll end up eating more throughout the day. That’s because a fast rise and equally sharp fall in blood sugar releases extra hunger hormones.

Your best bets for weight control are foods that are digested slowly, such as high-fiber grains, fruits and vegetables, and lean proteins such as low-fat milk, egg whites or low-fat sausage.

Steel-cut “old-fashioned” oatmeal, for example, is high in fiber and takes longer to digest than instant oatmeal. It also keeps you satisfied longer.

True, according to a 2005 University of Texas Health Science Center study. Researchers found that each can of diet soda participants drank per day was associated with a 41% increase in obesity risk – a greater rise than sugared soft drinks themselves caused.

A 2008 Purdue University study may offer an explanation: Rats that ate yogurt sweetened with saccharin consumed more calories overall and gained 20% more weight than rats that ate yogurt sweetened with glucose (a simple sugar).

The problem? Though they were getting fewer calories from the artificially sweetened yogurt, they ate more of it.

The researchers also discovered that the saccharin-eaters showed a smaller rise in body temperature after eating a sweet-tasting, high-calorie meal. That meant they didn’t get the same metabolic boost that would have helped them burn off the calories.

Escape the trap: Reset your beverage sweet toothWhether it’s due to sugar, high-fructose corn syrup, NutraSweet or Splenda, most soft drinks are as sweet and useless as candy. And if you get used to that level of sweetness, it’s hard not to look for it in other foods.

The solution is to ditch the diet pop and substitute no-calorie, flavored bubbly waters like Crystal Geyser’s Very Berry or Schweppes’ Lime Seltzer. Or make your own healthful drink by mixing half a glass of plain soda water with real berry juice.

If you’re used to adding loads of sweetener to your coffee or tea, work your way down to a single packet.

Better still: Skip the sweetener entirely – after a while, you won’t even miss it – and drink plenty of plain water. Not only is it natural, healthful and refreshing, it can help you lose weight all by itself, according to a 2010 Virginia Tech study.

When participants on a 12-week diet drank two cups of water before each meal, they lost about 4-1/2 pounds more than those who didn’t – and they kept the weight off for a year afterward.

What’s Your Diet Downfall?You already know if you're a junk food junkie or a sucker for bread and butter. You know if you've got a sweet tooth or a salty incisor. So what else is there to know about why your diet isn't working? Find out if you're unwittingly sabotaging your weight-loss plan and adding inches to your waistline with this diet quiz.

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